1. Field of the Invention
The present invention relates generaly to the field of electric power controller apparatus and, more particularly, to such apparatus having a manually-on and a manually- and electrically-off circuit breaker which controls one or more power outlets.
2. Discussion of the Prior Art
Many different electrical (or electronic) systems are known which are comprised of a number of different pieces of separately-powered electrical equipment. As an example, a computer system may comprise a main frame computer, several disc drives, and one or more work stations. As another example, a typical sensor system may comprise a number of separately-powered sensors, a well as a monitor or controller.
In some instances, all the different pieces of electrical equipment comprising a particulr system may be separately plugged into building power outlets. On the other hand, it is often preferred that all, or at least some, of the different pieces of electrical equipment comprising a particular system receive power from a common piece of electrical equipment commonly called a power controller. By means of such a power controller, the pieces of electrical equipment powered thereby may be turned on all at once or in some preestablished manner. For example, U.S. Pat. No. 4,719,364 to Pequet, et al., discloses an electrical power controller apparatus which provides a plurality of time-delayed power outlets which enable a like plurality of different pieces of electrical equipment to be powered-up (that is, turned on) in a predetermined time sequence with time delays possible between each turn-on. In turn, U.S. Pat. No. 4,769,555, also to Pequet, et al., discloses a power controller apparatus which provides both time-delayed powering-up and powering-down of electrical or electronic equipment which is connected to the apparatus.
In some electrical systems, it is desirable to have a power controller which shuts off all of the pieces of electrical equipment powered thereby in the event an emergency, an out-of-control, or some other preestablished condition occurs. As an illustration, it may be desirable for the power controller to turn off the equipment powered thereby if the line voltage supplied through the controller increases or decreases beyond preestablished limits in order to reduce the risk of electrical damage to the controlled equipment. In this regard, it is, for example, often the case that computer disc drives can be damaged if the driving voltage decreases significantly below its normal 110 or 220 volt level.
However, it may, at the same time, be undesirable to automatically power-up the controlled equipment when the emergency or out-of-control situation ceases or is cured. Instead, it may be preferred, once an emergency or out-of-control situation has caused the electrical equipment connected to the power controller to be shut down, to check out the system before the equipment is powered back up. In order to accomodate such a mode of operation, it is advantageous if the power controller is configured for automatic, electrical turn-off but for manual-only turn-on. Normally, it is usually desirable that the power controller also have the capability for manual turn-off so that the equipment connected to the controller can be powered down at will by an operator.
It is, however, difficult to provide economical power controllers which can be automatically turned off by electrical power when the situation necessitating the turn-off is failure of line power to the controller.
A principal objective of the present invention is, therefore, to provide a relatively inexpensive power controller which provides for automatic, electrical turn-off even when line power to the power controller is disrupted.